Cable television video messaging system and headend facility incorporating same

ABSTRACT

A cable television video messaging system for selectively overlaying or substituting a desired input message, for example an Emergency Broadcast System warning, onto multiple channels of a cable television system having a headend system where multiple external program signals are channelized by means of individual channel modulators. This achieved by a digital microprocessor powered message-management unit programmed to talk to a network of channel message units, one for each channel. Preferably the channel message units are also microprocessor powered and include character generator and channel synchronizer chips. General supervision of a cable television system&#39;s analog domain program distribution system by digital means is also possible.

TECHNICAL BACKGROUND

The present invention relates to cable television messaging systems which have the capability to override or supplement standard programming output to subscribers on one or more selected multiple channels with an audio message or a video message, or both. More particularly, the present invention provides a novel system for disseminating emergency alerting information to the public, enabling cable television to participate in that is currently known as the Emergency Broadcast System, in accordance with rules of the Federal Communications Commission (FCC).

BACKGROUND OF THE INVENTION

In 1992 typical cable television systems or program distributors, were operating an average of over thirty channels each and many stations, or rather, systems, fully expect to be operating or supplying hundreds of channels in the near future. Technical developments relating to digital data compression and multiplexing of program channels over optical fiber cables, which are being installed, promise the availability of thousands of cable television channels in the not too distant future.

A typical cable television system comprises a program management and administrative center and what is known as a headend where the image signal distribution equipment is installed. At the headend, incoming programs received by various means such as satellite transmission and antenna pickup, or generated locally and supplied from tape or over hard wire from a studio, are coordinated and distributed out to subscribers over individual program channels. Individual channels typically comprise a channel modulator adapting the audio and video signals to the appropriate frequency band for that channel. The channel modulators output into a combining network that feeds the signal into a cable distribution system for distribution to subscribers.

Very often, if not usually, the headend operation is remote from the programming and administrative center and is unattended, being operated electronically without the presence of a human operator. The automated operation of the cable television headend, and other technical considerations, raise difficulties in providing occasional or periodic override messaging of the output programming signals on a given channel. The difficulties are compounded if selective channel messaging, rather than blanket messaging of all channels, is desired. A particularly important override message is an emergency alerting signal in audio or video form. Under current regulations, a television, or radio broadcast station, as a condition for an FCC license must have a human operator on duty, and responsible for processing emergency alerts, whenever the station is on the air. This operator responds to various types of emergency alerting inputs and actuates the station emergency messaging in accordance with the operator's judgment, having regard to established emergency agency rules and station policy.

A customary alert signal, indeed the standard national Emergency Broadcast System tone is a two-tone signal which is transmitted on a weekly basis, as a test signal, with a standardized message alerting the public to the fact that a test of the Emergency Broadcast System is taking place. This test signal is familiar to most people in the USA. In the event of a national emergency, for which the system has, at this writing, never yet been activated, it can reasonably be expected that all people tuned to a broadcast television or radio signal will be reached with an audio message describing the emergency. With the growth of cable television and cable television programming, large sectors of the population are viewing non-broadcast channels not accessed by the Emergency Broadcast System.

Means do exist for transmitting emergency broadcast signals over the cable television distribution system to viewers. Where the cable television system is relaying a signal from a television station broadcasting radio frequency signals over the airwaves, any emergency signal transmitted by that broadcast station is also relayed to the cable television subscriber-viewer. However, as noted above, a typical cable television system includes tens of non-broadcast channels, supplied for example by tape, by movies, by local programs created by, or for, special interest groups, and so on. These viewers are not reached by the Emergency Broadcast System, unless the cable television system takes measures to override its non-broadcast programming with emergency alert information or messages. Lacking such alert information, there may be serious delays before these non-broadcast channel viewers become aware of impending natural disasters such as hurricanes, tornadoes and flash floods, or are alerted to threats to their safety from riots, prison escapees and the like, or referring to the fears that gave birth to the Emergency Broadcast System, before they are notified of military threats, including nuclear missile attacks.

Noting especially the proliferation of channels, and noting also the modest size of some cable television systems, (recent data indicate that over 60% of cable television systems have less than 1,000 subscribers) technical difficulties and significant costs arise in providing a cable television message override system. It has been estimated by the Society for Cable Television Engineers (SCTE) that headend upgrades to handle both audio and video Emergency Broadcast System signal delivery, based on the equipment available prior to the present invention, could total nearly half a billion dollars for the U.S.A. (see, for example, Cablevision p. 15, Jul. 5, 1993, "Revving Up a Test Drive For EBS").

Means also exist for conveying emergency alerts to viewers of non-broadcast cable television channels but known means are limited in functionality, are not all-encompassing and do not reach all viewers.

It is present policy of the FCC to bring all cable television viewers within the ambit of the Emergency Broadcast System, or of a renamed nationwide emergency alerting system, and guidelines or regulations for achieving this aim are expected to be promulgated shortly. These guidelines include performance parameters for a new "device" or devices for overriding non-broadcast cable television channels with emergency alerts. Relevant FCC activities are proceeding under FO Docket #91-301 and FO Docket #91-171. The latest publicly available document from the FCC under this heading, of which applicant is aware, is a "NOTICE OF PROPOSED RULEMAKING/FURTHER NOTICE OF PROPOSED RULEMAKING" released Oct. 8, 1992 ("NPRM/FNPRM").

On Jan. 15, 1993, a document entitled "COMMENTS OF THE SOCIETY OF CABLE TELEVISION ENGINEERS" (SCTE Comments) was filed by counsel for the SCTE, in the aforementioned FCC docketed matters. The SCTE Comments describe existing Emergency Broadcast System technology for cable television and remark upon the FCC's proposals as to possible performance criteria that might be attained by new equipment. The comments are apparently the collective input of those skilled in the art of cable television engineering, being members of the SCTE. This document apparently represents the state of the art of this topic at Jan. 15, 1993.

Programming override equipment for emergency alert messaging, as currently installed in cable television headend facilities, is described in Appendix A of the SCTE COMMENTS, which information is summarized herein by reference to FIGS. 1 and 2 of the accompanying drawings.

FIG. 1 is a schematic depiction of what is known as a "carrier-substitution method" for emergency alert messaging on cable television systems. This carrier-substitution method is widely utilized in currently operating cable television Emergency Broadcast System equipment, according to the SCTE. The alternative method is known as "channelized override", and is described with reference to FIG. 2.

Referring to FIG. 1, carrier-substitution systems employ a group of substitution carriers 10, one for each channel, which are referenced 10, to replace the cable television's headend carriers during an emergency notification.

Substitution carriers 10 are coupled to receive audio from a telephone answering device 12, and are available on standby as an alternative to a headend system 14, providing normal programming to the cable system through a switch control 16.

In the event of an emergency, an authorized official appointed by the cable television system calls the cable television headend over a standard, DTMF, touch-tone telephone which activates the telephone answering device 12.

Entry of appropriate codes causes the telephone answering device 12 to operate switch control 16 replacing the programming signals from the headend system with the substitution carriers 10 and feeding them out over the cable system to subscriber-viewers. Depending upon the system, the official's voice can be fed across the telephone lines to modulate the substitution carriers. Viewers of every channel hear the official's message as voice-modulated audio is input to the cable system. At the same time, video on every channel is overridden with a black or blank screen. The message terminates with deactivation by the official entering a turn-off code or hanging up the telephone.

In summary, this commonly used carrier substitution system completely replaces the program signal, eliminating all video from the viewer's screen. This is undesirable, unduly dramatic and may cause many viewers to panic, fearing the emergency has already affected their television reception. The audio only option is to feed the official's voice to all channels; which may override more detailed, more accurate or more relevant warnings carried by broadcast channels that are being relayed on the cable television system.

The channelized override system of the prior art shown in FIG. 2 is also activated by a touch-tone telephone to which a telephone answering device 12 responds, activating switch control 16 in response to the proper touch-tone code, whereupon the telephone audio message overrides the program audio on all channels. In this case, in contrast to the simpler carrier-substitution method of FIG. 1, the override audio and an optional override video signal are superposed or overlaid on the program carriers, rather than substituting them. The override signals are supplied to an intermediate frequency modulator 17, passed to a splitting network 18 which raises and splits the signals to the requisite number of frequencies channels. Each program override signal is switched through a respective cable television modulator-processor 19 where it replaces the program signal. The output of each modulator processor is fed through the cable system's combining network 21 for transmission to viewers.

This method is much more costly than the carrier substitution method because the override is effected separately for each channel at channel frequencies which are typically in excess of 50 MHz whereas the substitution carrier method employs a common RF override.

An advantage of the more expensive channelized override approach is the option of selectively overriding a predetermined number of channels. However, a further drawback of this known channelized override system is that the selection of channels to override is fixed, being made permanently when the channel override hardware is installed, and cannot be automatically or dynamically redetermined.

A further advantage of the channelized approach is the provision of an optional video output as an alternative to a blank screen. This option requires additional equipment for each channel, for example a text-character generator, or live video, if this is available.

In general, the channelized override approach is expensive because program-frequency override signals have to be created separately for each channel, at the headend, means for which are not normally a part of a cable television system's equipment. As reported by the SCTE, cable stations do not generally have a source of live video, although, in some cases, this may be delivered from an activating authority.

Commencing at page 7 of their comments, the SCTE make proposals for design parameters for a new emergency alerting device complying with the proposed FCC requirements, or a close modification thereof. Such a hypothetical device could, according to the SCTE, be a universal device for AM and FM broadcast TV as well as cable television, and should have card slots and optional modules to be able to be tailored for diverse applications and user requirements. Further according to the SCTE, a two-tone emergency warning generator should not be necessary as this tone should be passed through from a broadcast source, and the system should be activatable by a telephone DTMF signal. A capability directly to turn television sets on and off from an incoming cable signal was seen as undesirable.

The hypothetical device would contain intelligence to code addressable information and to act to activate override equipment to pass through emergency information received. The device should be programmable with regard to a rating of the seriousness or impact of a given incoming alert or test, to determine the degree of channel override. This alert level setting by local programming should permit national activation. The device should be capable of receiving emergency information from multiple sources, for example: a CPCS-1 station; NLAA weather radio; state government; local authorities such as the mayor, or city or county emergency management office; or state police, local police or fire departments and the like.

A basic device before options should have connections and associated electronics to receive activation signals and emergency information messages from the local NOAA weather radio frequency, the local AM broadcast CPCS-1 frequency, and via a twisted pair connection. The purpose of the twisted pair input is to enable equipment in cable television headends which is currently accessible to local authorities via telephone connections, to be utilized.

Optional features could include additional inputs from audio and video signals from external sources for example satellite, microwave, or cable links, and AM or FM television broadcast. Optional feature could also include a data port, for example, an RS 232 connection for receiving digitized signals and for those areas having designated local emergency alerting frequencies, the capability of adding an auxiliary RF receiver could also be included.

The hypothetical specification continues with the parameter that once a signal is received, by the device through any one of the aforesaid inputs, the signal is decoded to retrieve address information, implying that incoming signals from all input ports need to be sampled by decoding circuitry. Recommended was the ability to decode two types of signals, namely, standardized digital encoding such as WRSAME coding implemented by NOAA weather radio and DTMF telephone signals to permit utilization of existing equipment.

The hypothetical device is further specified as having necessary electronics and connections to support a contact closure output and an audio output. The contact closure output would be activated in response to an alert signal by the device to activate whatever program override equipment is utilized by the participant. The audio output would serve to pass through emergency information transmitted by an activating entity.

Optional additional outputs include video output for an emergency video signal; a digital output to feed ASCII text for video crawl messaging; an additional data output port, for example an RS 232 and the necessary electronics could be included to provide verification of receipt of an activation signal and of override of programming; a printer or modem, or both.

All these characteristics are no more than desirable goals. No engineering, no circuit design, no principles of design or operation of a device that could comply with these elaborate parameters, are disclosed or suggested by the SCTE.

Noting the proliferation of cable television channels, and that this is a niche market with optimistic potential product runs only in the low thousands, because of the number of cable television systems to be supplied, new override equipment comprehensively meeting all the FCC and SCTE parameters is expected to be extremely costly, so costly as to be prohibitively expensive for smaller cable television facilities, such as those with fewer than a thousand subscribers.

SUMMARY OF THE INVENTION

The present invention solves a problem. It solves the problem of providing an economical cable television messaging system that can override or substitute a video message on a multi-channel cable television system in a selective manner suitable for delivering public emergency alert information to practically any member of the cable television audience.

The above problem is solved by an inventive system which is readily able to receive emergency alerting, or other, messages from multiple sources and to be activated by remote electronic signals, for example, personal computer output or DTMF touch-tone telephone input.

In accordance with the objective of solving one or more of the foregoing problems, the invention provides a cable television video messaging system for selectively overriding a desired input message onto multiple channels of a cable television system having a headend system where multiple external program signals are channelized by means of individual channel modulators having program signal input ports and exported to cable for transmission to a subscriber audience. The inventive video messaging system comprises:

a) a remotely activatable input message decoder to receive, from multiple sources, incoming message information regarding a video message to be overlaid on at least one channel, said message decoder decoding message descriptors embedded in or accompanying said incoming messages;

b) an intelligent message-management device for routing messages to at least one designated channel according to said message descriptors and in accordance with system-based instructions; and

c) a video injector to combine said message video with program video for said designated channel to produce a channelized combined video message;

wherein said channelized combined video message is supplied to said channel modulator program input port.

Preferred embodiments employ a digital supervisory and display management system that can be embedded on existing program distribution equipment in a cable television system's headend facility. The invention extends to a headend facility equipped with the inventive video messaging system.

Surprisingly, I have found that, although low cost is an important consideration in making my invention, the expense of digitizing the message input and then separately converting each channelized output to an analog signal output compatible with the program signal, is more than outweighed by the benefits gained. In particular, by employing microprocessors in conjunction with significant data storage capability linked to one another in a data network, the embedding of a digital loop to control an analog processing system brings with it the advantages of digital control. Surprisingly, within the confines of a low-cost, moderate production volume system, I am able to gain the advantages of computer control, along with software programmability of many of the system functions.

A major difficulty in bringing the advantages of inserted video messages to multi-channel cable television systems, lies with the expense of providing separate messaging equipment for each channel. This difficulty is compounded in attempting to bring the benefits of computer management to a cable television headend facility. While the cost of a centralized personal computer used to perform control functions at the headend, which cost will probably be several thousand dollars when allowance for specialized video or audio-video boards is made, may not be unreasonable, the cost of servicing every one of tens of channels with personal computer equipment may be prohibitive.

A further difficulty in providing computer management of cable headend facilities lies in the difficulty of devising suitable interfacing between control systems operating in a digital domain, and tens of continuously supplied video program signals processed in an analog domain, while ensuring that digital control, or supplementation, does not result in unintentional interruption of any program signal. This problem is also solved by the systems of the invention. These advantages are achievable by employing microprocessor units programmed preferably in an assembly language and wired together, through communications interfaces, or otherwise in communication, so that physically separated units can talk to one another to interchange addressed digital data packets. Thus, in a preferred embodiment, the invention provides a microprocessor-equipped message-management unit, or with inputs for receiving a variety of coded or decoded message management information. The message-management unit outputs messages, preferably in digital form, labeled with one or more channel addresses according to what channels have been designated to display a given message.

Receiving channels are each equipped with a channel message unit to receive a message addressed for that channel, in digital format, and to overlay or substitute that message, in analog form, on the program video output. Preferably, the channel units each have an audio and a video connection with a modulator unit for that channel. These connections can be with customary jacks, for retrofitting or, alternatively, the channel units could be built in, or incorporated with the modulator units, as original equipment.

Channel message units according to preferred embodiments of the invention are also microprocessor equipped and recognize appropriately addressed messages from the message-management unit. A further problem in messaging multiple cable television channels is that television channels are asynchronous. This means that an overlaid moving text cannot be put out in a common format to every designated channel. Preferred embodiments of the invention solve this problem by providing synchronization means in each channel unit to synchronize a message signal to the channel's horizontal and vertical characteristics.

The message-management unit is preferably adapted to receive the message management information from multiple sources. The message management information can include message content, or location information specifying where the message content is to be found, along with prioritizing or rating information from which the system can, according to predetermined inputs, select a channel or group of channels on which to display the message.

In general terms the CATV messaging system of this invention provides a digital supervisory and message display system embedded on or overlaid on top of the conventional video signal distribution system of a cable television service.

In preferred embodiments, channel units are connected to a message-management server to form a distributed local area network within the cable headend, and are positioned as a unit to receive normal cable television system input and to output to the cable system.

While the invention is applicable to the distribution, in a selective manner, of one or more incoming audio messages, among desired cable television channels, without an accompanying video message, preferred embodiments employ the enhancement of video to improve the message's impact, and therefore effectiveness, on the viewer, and to enhance the value of the equipment to the cable television service. Bearing in mind that emergency alerting systems are subject to regular testing, it is important that the message form be acceptable to most viewers, and not unduly annoying.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some embodiments of the invention will now be described, by way of example with reference to the accompanying drawings, in which similar reference numerals depict similar structural features, and:

FIGS. 1 and 2 are conventional programming override equipments for emergency alert massaging.

FIG. 3 shows a schematic layout of a cable television system's headend system or headend facility equipped with a cable television message system according to the invention;

FIG. 4 is a view similar to FIG. 1 of another embodiment of cable television message system according to the invention which is more suitable for larger facilities;

FIG. 5 is a view similar to FIG. 1 of a still further embodiment of cable television message system according to the invention which is more suitable for smaller facilities;

FIG. 6 is a front elevation of a channel message unit depicted schematically in FIG. 4;

FIG. 7 is a rear elevation of the channel message unit of FIG. 6;

FIG. 8 is a schematic view showing a possible arrangement of communications and power channels between a message-management unit and channel message units;

FIG. 9 is a front perspective view of a message-management unit depicted schematically in FIG. 4 or FIG. 5;

FIG. 10 is a rear perspective view of the message control unit of FIG. 9;

FIG. 11 is a schematic view of one possible physical disposition of the channel message units of the inventive system, at a cable television headend facility;

FIG. 12 is schematic or block diagram of a programmable, intelligent, audio-video injector unit, which can function either as a message-management unit or as a channel message unit in the preferred embodiments of the invention described with reference to FIGS. 3-11, depending upon how it is programmed; and

FIG. 13 is a circuit diagram of the intelligent audio-video injector unit of FIG. 12.

The cable television messaging system shown in FIG. 3 is intended for distributing Emergency Broadcast System alerting bulletins or other messages in audio and video form. Preferred embodiments receive a digital message and output the message as a video text crawl on multiple selected channels. The inventive system decodes incoming messages or message alerts received from a variety of possible sources, determines which channel or channels should receive each message and routes the message accordingly. The inventive system can also generate message video to override, or combine with, base band program video signals.

According to the invention, these steps are carried out prior to modulation of individual channel signals, and a message-bearing combined signal is supplied to each one of a cable television's customary headend system's channel modulators, for the channels designated to receive a particular message.

A feature of the invention lies in intercepting program signals prior to each channel modulator, and selecting the modulator program signal input port as a point of insertion for the supply of a messaged program signal. A preferred embodiment employs individual channel message units for this purpose, and preferably these channel units are controlled by a centralized message-management unit with which the channel message units communicate, which message-management unit supplies addressed message information, including, possibly, message content.

Overall system cost can be controlled by minimizing the functional requirements of the channel units, moving as much functionality as practicable to a centralized message-management unit. For most services with substantial numbers of channels, reducing the cost of the channel units, which are needed one for each channel, will represent a significant saving in delivering a quality video message to selected channels.

Referring to FIG. 3, the inventive cable television messaging system shown comprises a message control decoder 20 which is connected or connectable to receive a variety of communications inputs, for example digital signals embedded within a broad casted signal received from an AM receiver 22, an FM receiver 24, a microwave receiver 26 and a satellite receiver 28 as well as DTMF control signals and audio overlays via a telephone modem 30. Any of these communications inputs 22-30 can carry an incoming emergency alert signal or other incoming message overlay signal, (which may be a substitution signal completely rather than partially replacing the base program signal) to the message control decoder 20. While at the time of this application, these inputs are usually in analog form, it is expected that emergency alerting messages in particular, may be disseminated in digital format in the future, which digital messages can also be received by the decoder or other components of the present invention.

Message control decoder 20 decodes address and control information associated with an incoming message overlay system and relays the message overlay system to a designated channel or channels through a channel message inserter 32. Channel message inserter 32 also receives channel program information from channel inputs CH-2, CH-3 to CH-N, "N" representing the total number of television channels provided by the cable television system, there being, as shown, one channel message inserter per channel. Each channel message inserter 32 incorporates an audio switch to select between program and message audio and outputs a channel signal to channel modulator 34.

The content of the output channel signal depends upon instructions received from the message control decoder 20 and will comprise normal program information until an override signal is detected by message control decoder 20, whereupon the audio or video signals, or both, that are output to a channel modulator, or modulators 34, for a designated channel or channels, are overlaid or substituted with an incoming, appropriately coded, message, for example, an emergency alert. The output of channel modulators 34 is supplied to a cable system, for distribution to subscribers, through a television combining network 36, in conventional fashion.

To comply with FCC requirements intended to incorporate cable television into the national Emergency Broadcast System, or a renamed such system, audio switching to provide a voiced alerting message overriding or replacing program audio, will be necessary, but a video overlay is expected to be optional. However, greater flexibility and product functionality is obtained by providing means for each channel message inserter 32 to insert a video message which can, preferably, be, or include, a text, especially a crawl text moving horizontally.

If desired, a details message can be supplied to a preselected cable information channel CH-X, via a details message inserter 38 activated from message control decoder 20. Other channels can carry messages referring viewers to the details channel in the event of an emergency.

The inventive CATV (cable television) message system embodiment depicted schematically in FIG. 4, installed in a multi-channel cable television headend, is suitable for large and medium-sized cable television systems. The novel CATV message system provides the ability selectively to override multiple channels with both audio and video messages, especially for example, with emergency alerting messages. Here, as with the FIG. 3 embodiment, individual channel modulators 34 feed channel signals into a combining network 36. Message signals are received via an AM line 40 and an FM line 42, through a message control decoder 44, which functions as an Emergency Broadcast System decoder and responds to emergency alerts when these are received.

In this embodiment, management of audio and video message override or insertion is shared between a centralized channel messaging base unit or message-management unit 46, and individual channel message units 48 connected on an open network with message-management unit 46 to receive addressed control and message information therefrom. Preferably this information is digitized to be susceptible to computer manipulation.

Message control decoders 20 and 44 are intended to operate in accordance with FCC EBS device requirements and can be constructed in any manner as will be apparent to those skilled in the art.

Some possible inputs to message-management unit 46 comprise the decoded output from message control decoder 44 and cable system audio and video message sources 50 and 52 respectively. Thus, for example, the message control decoder may recognize what type of message is coming in, full page, horizontal crawl, foreign language, e.g. Spanish, etc, or perhaps, audio only. Message-management unit 46 then determines what should be done with the decoded message. For example, a Spanish-language message is probably intended only for a Spanish-language channel, and is so-designated by message-management unit 46.

In addition, message control decoder 44 can include a contact switch actuator 54 to activate message-management unit 46, as well as digital input from message control decoder 44, if appropriate, for example over an RS 232 serial interface. A network, or direct, PC interface connection 56 and a modem interface 58 can also be provided, permitting the inventive channel messaging system to be remotely managed under computer control, or to receive instructions, or messages from a near or remote computer. Message-management unit 46 can also output an activity log, message copy or any other available information to a printer 60, if desired.

Message management unit 46 can provide a direct analog audio and video override signal to a details message channel 62, if desired.

Message-management unit 46 uses intelligent digital means, preferably a microprocessor, to manage distribution of incoming messages to the designated channels.

Each channel message unit 48 is also preferably microprocessor-equipped and has audio and video input connections to receive program signals 64, and output audio and video connections 66, to a respective modulator 34. Digital communication with message-management unit 46 can be over an RS 485 link. Channel message units 48 receive appropriately addressed digital messages from message-management unit 46, convert a received message to analog form, combine it with program video as appropriate, and output the overlaid or substituted signals to their respective modulators.

In an operational example, an emergency alert received by AM radio, in analog form, is decoded, its priority or other coding is read and passed to message-management unit 46 which interprets the priority code, sends an audio message, for example, an emergency official's voiced bulletin, also received over AM radio, to the channels appropriate to that priority. Video messaging is activated, digitized and sent out to the respective channel units where the digitized message is synchronized for that channel and output as analog and overlaid on the program signal, for example, as a horizontal text crawl.

This system permits dynamic scripting on multiple channels. Simpler systems suitable for emergency alerting can provide a single line of text moving across an otherwise uninterrupted program screen. More sophisticated systems can include a graphics processor in both the message-management unit 46 and each channel control unit 48, separately to drive screen sub-divisions or windows and can be used, for example, to provide an onscreen window for passive, or interactive advertising messages from sponsors of programming, or for the cable system or channel to advertise its services or programming, or to sell classified advertising and the like.

The FIG. 5 embodiment, intended for smaller cable systems, is similar to the system described with reference to FIG. 4, except that, here, instead of outputting to individual channel message units, the output from message-management unit 46 is supplied to an intermediate frequency (IF) modulator 68, operating for example at 44 MHz, which downloads the message audio and video on to all channels for which the IF modulator 68 and CATV messaging system is installed.

The FIG. 5 system is unable to synchronize message video for individual channels, but provides a blank screen overlay on every channel, or more preferably a static, full-screen text message to accompany the audio message. It thus succeeds in supplying an emergency alert or other message to a group of television channels, being a group selected on installation, including both broadcast and non-broadcast channels, broadcast implying a channel relayed from a broadcasting rf station, via antenna pickup, which station is assumed to be a member of the Emergency Broadcast System.

In one application, the FIG. 5 embodiment breaks into all channels with a static (though possibly pageable) full-screen, preferably textual displayed message accompanied by a voice-over, the same messages being sent to all installed channels. If desired, the text message can tell viewers to turn to a different channel for more information about the emergency.

A suitable channel message unit 48, as shown in FIGS. 6-7, has, for external communication, READY, ACTIVE and TEST indicator lights 70 on its front panel; and on its rear panel a daisy-chained or serial-connected communications cable 72 networking to the message-management unit 46 and other channel message units 48, video input and output 74 and stereo audio input and outputs 76. Power can also be carried in communications cable 72, employing channels such as those shown schematically in FIG. 8.

FIGS. 9 and 10 show similar external communications for a message-management unit 46 which has an additional video input/output 78, and two serial data communications ports 80 with data-present indicators 82 and a power cable 84.

FIG. 11 shows a message-management unit 46 networked to a plurality of channel message units 48 mounted on racks (not shown) alongside the channel modulators 34, each channel message unit 48 being coupled, or wired to an adjacent modulator 34. Alternatively, the message units 48 could be arranged side-by-side, one with one another, on one or more racks. This may be more convenient when retrofitting the invention by coupling the channel message units 48 to existing channel modulators 34 in a cable television headend system.

The embodiment of FIGS. 12 and 13 exemplifies how a digital control circuit, equipped with a supplemental image source of message video can be embedded in a single unit with a base band video pathway to inject a video message on to the base band video producing a signal for a complex image having independently controllable image sources for split-screen, window and similar effects, and in the particularly preferred embodiment of the invention, for horizontally crawling a text message across an otherwise uninterrupted, continuously running program screen.

One way of programming the intelligent video injector is as a channel message unit 48. In this application, message video received in digital form is converted to a video signal synchronized, or otherwise adapted to the requirements of an intended cable television program channel, and output to a channel modulator, or other individual distribution point for that channel.

An alternative application of the intelligent video injector unit, achievable by programming, is as a message-management unit 46. In this case, a video message source or sources, is desynchronized, if necessary, digitized, packaged, processed and addressed according to an externally specified protocol, which can be derived from, or be responsive to a remote incoming signal or instruction, and output on a digital pathway for interpretation by channel message units 48, or, in the case of the IF system of FIG. 5, for interpretation by the IF modulator 68.

Other useful applications of the novel, intelligent video injector of the invention will be apparent to those skilled in the art. As will also be apparent from the following description, by employing microprocessors, and chip-based functional elements to perform individual video management and conversion roles, and by programming the microprocessors to communicate with one another along cabled data pathways, a compact economical unit, can be assembled on a single board and supplied in a small box complete with at least one data communications port and video input/output jacks and the like.

Such novel system units can also manage distribution of an audio message override to, control-message specified channels, for example by driving a chip-based audio multiplexer from a central or control microprocessor that also manages the video functions of the intelligent video injector.

Referring to FIGS. 12 and 13, a central microprocessor 90 functions as a control unit and communications center for both the digital and analog system phases, interface to the analog phase being made through one or more digitally drivable video chips for image generation, synchronization and the like.

Central microprocessor 90 is liberally supplied with ROM 92, for program storage and RAM 94, for processing usage. In a practical embodiment for providing message of fixed page, multipage or a video crawl, 32 Kb is adequate for both purposes. Use of an application-programmed microprocessor avoids the cost and bulk of employing a complete computer system or station at each network node point. Use of assembler or machine language, which is a preferred practice of the present invention, avoids difficulties arising from limitations of, and equipment capacity requirements of, operating and network systems, but does mean that off-the-shelf software modules cannot generally be employed. Assembler or machine language is highly efficient, imposing modest storage requirements and contributing to the efficiency, compactness and economy of the systems of the invention. An 8-bit commercially available microprocessor, is suitable for use as control microprocessor 90, for current text crawl applications.

External digital communication to central microprocessor 90 is handled by chip-based communications interface 96, and proceeds physically through a communications port 97, which is preferably an RS 232 serial port for external communication with the inventive messaging system. For communication, in network style, with other video injector units, a port 130 and associated cabling, preferably of RS 485 type, can be provided.

The common digital componentry provided in multiple video injector units, such for example as a message-management unit 46 and multiple, perhaps tens of, or even hundreds of, channel message units 48, namely central microprocessor 90, external communications interface 96 and port 97, with associated cabling or other remote communication means, and RS485-type unit-to-unit communication, coupled with ROM-stored programming enabling multiple microprocessors 90 to "talk" to one another, provides a shared network with distributed processing enabling common functions, such as implementing addressing instructions to be centralized, other functions, can be distributed to the channel units 48.

A video pathway extends between a video input jack 98 and a video output jack 100, and includes a component-based video amplifier circuit 102, a chip-based synch separator circuit 104, a character generator 106 and an emitter follower 108. A character setup circuit 110 interacts with character generator 106 to control its video output. Character generator 106 and a chip-based delay line 112 which outputs to, or talks to, character generator 106 and synchronizer setup 104, are controlled by, and communicate with central microprocessor 90.

Character generator 106 is on efficient means of generating message video for text crawl messages. If a more sophisticated message image is required, character generator 106 can be replaced by a graphics generator or other image generator or suitable video input which can be digitized and then regenerated in channel-compatible form through an appropriately equipped channel unit.

An audio pathway comprises a chip-based audio multiplexer 113, controlled by and communicating with microprocessor 90. Audio multiplexer 113 controls the passage of base band or program audio between audio input jacks 114 and audio output jacks 116. Message audio is received through message input jack 118 and output through message output jack 120. The system provides switching circuitry, including audio multiplexer 113, operating to switch between local audio and external audio sources such as FCC or FEMA supplied warning messages, as instructed by microprocessor 90.

In a message-management or server mode, such as to provide the message-management unit 46, the novel, intelligent video injector can additionally comprise one or more data ports for external communication beyond the network, for programming or message input, and can also comprise, on a common, or additional board, additional input/output devices for receiving messages from multiple sources and for different types of outputs including hard prints, activity reports remote operator alerting and the like.

However it is received at message management unit 46, central microprocessor 90 coordinates a message or messages with routing information that may be preprogrammed in ROM, separately supplied over a data channel, or coded into the video message. Messages are labeled with desired address information, for example in channel ID circuit 136, and any local processing instructions and output through the communications link constituted by communications interface 132, RS485 port 130 and associated cable links, to data-sharing channel message units 48.

In channel message unit mode, as determined by its programming and installation, the video injector receives appropriately addressed messages through its communications link comprising communications port 97 and communications interface 96 into RAM 92 of central microprocessor 90.

Central microprocessor 90 coordinates and controls the insertion of the desired message into baseband, program video received through video input jack 98 and the output of the compound signal through video output jack 100. For a horizontal crawl text message, character generator 106 is supplied from RAM 94 with digital message text for conversion to video characters.

Characters size are determined by information provided by microprocessor 90 to the character generator 90. Character generator 90 is synchronized to the intended channel's horizontal and vertical characteristics by signals from the sync separator 104. Timing of the message, to flow the characters across the screen is effected by delay line 112 acting on sync separator 104 and character generator 106 under the control of microprocessor 90.

The microprocessor and chip-based systems of the invention have been found to produce excellent quality text crawl messaging. As compared with character generation at a broadcast station picked up and relayed by a cable television service, messaging generated by the herein described systems of the invention gains quality, (or avoids airwave quality losses) from direction injection into the cable distribution system, which is often fiber optic.

Received message audio is routed through multiplexer 113 to specified channels, as designated by central microprocessor 90. If desired, multiple messages can be synchronized to multiple, different screen regions to create a composite message screen or composite image screen made up of a base band image and a plurality of injected images. As at present envisaged, multiple video injector devices will be needed for each channel, one for each added image segment. However, advances in processing equipment and techniques, may enable multiple image segments to be processed simultaneously.

A further advantage of the invention is an ability to sense the presence of a video carrier signal on any one or more channels. If microprocessor 90 reports that no signal is present, indicating a loss of video on that channel, a substitute default video text message can be automatically inserted by the messaging systems described herein, for example, "Please Stand By. Normal programming will resume as soon as possible."

It may be seen from the foregoing disclosure that, rather than significantly modifying a cable television service's equipment, the inventive messaging systems provide a digital supervisory and display system for the cable television service which system can easily be embedded on top of existing, analog-processing, program distribution systems.

The digitally based control and display systems for cable television facilities provide much more than just a new ability to distribute emergency alert messages, they provide cable television system operators with new means to control and manage their headend facilities. The channel message units can not only insert messages but, with suitable programming, and the addition of diagnostic circuitry, because they read the program signals and have the ability to communicate centrally in digital format, can provide detailed and extensive on-line reporting of channel activities including program signal quality characteristics, signal strength, interruptions, changes and the like, as well of course as usage of the messaging, which, if paid, can be used for billing sponsors.

While an illustrative embodiment of the invention has been described above, it is, of course, understood that various modifications will be apparent to those of ordinary skill in the art. Such modifications are within the spirit and scope of the invention, which is limited and defined only by the appended claims. 

I claim:
 1. A cable television video messaging system for selectively inserting a desired input message into respective program signals output on multiple channels of a cable television system, said cable television system having a headend facility where multiple external program signals are channelized by means of individual channel modulators having program signal input means and are exported to a cable network for transmission to a viewing audience, said video messaging system comprising:a) a remotely activatable input message decoder to receive, from multiple sources, incoming message information regarding a video message to be displayed on at least one channel, said message decoder decoding message descriptors embedded in or accompanying said incoming messages; b) an intelligent message-management device for routing messages to at least one designated channel according to said message information and in accordance with system-based instructions; and c) a video injector to combine said video message with a baseband program video signal for said designated channel to produce a channelized messaged program video signal;wherein said channelized messaged program video signal is supplied to said channel modulator program input.
 2. A video messaging system according to claim 1 embodied as a digital supervisory and display management system capable of being embedded on existing program distribution equipment in a cable television system's headend facility.
 3. A cable television headend program distribution facility having installed therein a video messaging system according to claim
 1. 4. A cable television video messaging system according to claim 1 wherein said channelized messaged program video signal is selected from the group consisting of a full-screen replacement message, a stationary screen overlay message, a crawl text overlay message and a graphics overlay message.
 5. A cable television video messaging system according to claim 1 wherein said video injector unit comprises:a) an input for said baseband video program signal; b) an output for said messaged program signal; c) an intelligent processor with data storage to control said video injector unit and to receive and output a digital message; d) an image generator to receive said digital message output from said intelligent processor and to generate said video message from said received digital message;wherein said image generator inserts said video message into said baseband video signal to provide said messaged program signal.
 6. A cable television video messaging system according to claim 5 wherein said image generator comprises a character generator to receive digital characters and output video text characters and a character delay circuit to generate a crawl text message.
 7. A cable television video messaging system for selectively inserting a desired input message, in crawl text mode, into a respective program signal output on at least one selected channel of a multi-channel cable television system, said cable television system having a headend facility where multiple baseband program signals are channelized by means of individual channel modulators having program signal input means and are exported to a cable network for transmission to a viewing audience, said video messaging system comprising:a) a message input to input a digitized text message and to input at least one channel address for delivery of said digitized text message; b) an intelligent message-management device for routing said digitized text message to said at least one channel address; and c) a video injector for each said channel addressed to combine said digitized text message with a baseband program video signal for said designated channel to produce a channelized messaged program video signal, said video injector comprising:i) a character generator to convert said digitized text message to a video text message; ii) timing circuitry to crawl said video text message horizontally across a television display; and iii) message insertion circuitry to combine said video text message with said respective baseband program signal;wherein said message management unit and each said video injector unit are interconnected to communicate messages in addressable digitized network manner and wherein said channelized messaged program video signal is supplied to a respective channel modulator program signal input. 